Known trucks typically use drum brakes or disc brakes, or a combination of drum and disc brakes, to slow the vehicle when required.
EP1473481 shows a known disc brake assembly that has a carrier with just a leading edge abutment and a trailing edge abutment for each brake pad. When the associated vehicle is travelling in a forward direction, the brake is applied and the brake pad drag torque on the inboard brake pad is reacted entirely by the abutment on the trailing edge of the carrier. When the vehicle is travelling in a reverse direction, the brake is applied and the brake pad drag torque on the inboard pad is reacted entirely by the abutment on the leading edge of the carrier. This is the case when the brakes are applied relatively lightly or relatively heavily.
US2006/0060431 shows a light vehicle caliper which is hydraulically operated. The arm of the caliper passes over the top of the brake pads, and in order to remove and replace the brake pads the caliper must be removed from the vehicle.
Trucks have a primary direction of movement, i.e. they primarily travel in a forward direction, and as such the brakes operate almost exclusively when the vehicle is travelling in a forward direction. While the vehicle can travel in a reverse direction, this typically occurs only occasionally and when it does so the vehicle will be travelling at a low speed thereby causing very little wear on the brake pads/shoes.
When a disc brake assembly is fitted to such a truck, a brake disc rotates within a space created between two brake pads. Because the vehicle has a primary direction of travel, each brake pad has a leading edge and a trailing edge, i.e. when the vehicle is travelling in the forward direction a point on the brake disc friction surface will approach the leading edge of the pad first, then pass under the brake pad and depart from the trailing edge of the pad.
The brake pad typically includes a friction material attached to a brake pad backplate. Clearly, when the brake is applied, a drag torque is created at the interface between the disc friction surface and the pad friction surface. This drag force is typically reacted by the brake pad backplate near the trailing edge of the pad.
When new, typically the brake pad backplate is flat and the brake pad friction material will be of constant thickness. In some brakes the friction material can tend to wear unevenly, in particular it can wear in a taper fashion with the leading edge wearing faster than the trailing edge, i.e. in a tangentially tapered fashion. This results in a brake pad becoming unusable (i.e. worn out) earlier than it might otherwise become had it worn in a parallel, i.e. non taper fashion.
The present invention seeks to mitigate or at least partially mitigate the problem of taper wear on brake pads.